Unity 4.6 - Rotating with Mouse Issue

I am trying to create a "dial" element, which can be used for various cases in Unity 4.6 UI. I have the dragging working, however for some reason, the rotation following the mouse is difficult, not letting the mouse rotate the button around a full 360.

 public GameObject texture = null;
     
      private float angle = 0;
      private Vector2 pos = new Vector2(0, 0);
      private Rect rect;
      private Vector2 pivot;
      private bool rotating = false;
      private float initialMouseAngle;
      
      void Start() {
          rect = new Rect(texture.transform.localPosition.x - texture.GetComponent<RectTransform>().sizeDelta.x * 0.5f, texture.transform.localPosition.y - texture.GetComponent<RectTransform>().sizeDelta.y * 0.5f, texture.GetComponent<RectTransform>().sizeDelta.x, texture.GetComponent<RectTransform>().sizeDelta.y);
          pivot = new Vector2(rect.xMin + rect.width * 0.5f, rect.yMin + rect.height * 0.5f);
      }
   
        void Update() {
          Vector2 guiMouse = Input.mousePosition;
 
          if (Input.GetMouseButtonDown(0)) {
              Vector2 v2T = ((Vector2)guiMouse - pivot);
              initialMouseAngle = Mathf.Atan2(v2T.y, v2T.x) - angle * Mathf.Deg2Rad;
              rotating = true;
          }
          else if (Input.GetMouseButton(0) & rotating) {
              Vector2 v2T = ((Vector2)guiMouse - pivot);
              angle = (Mathf.Atan2 (v2T.y, v2T.x) - initialMouseAngle)  * Mathf.Rad2Deg;
          }
          else if (Input.GetMouseButtonUp(0)) {
              rotating = false;
          }
 
           texture.transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);
 
      }